----- water of this pond is clear. Use article.

The correct word for the blank is could. The completed sentence is: "We worked hard so that we could succeed." 

The correct sentence is :-"I look forward to hearing from you."

"blue blood" correctly means aristocratic birth, or being of a royal, noble, or socially prominent family.

the passive form of "Do it as I say" is Let it be done as I say.

The correct verb form would be taking. The completed sentence is: "Would you mind taking simply a cup of coffee?" 

• Advise verb-এর পরে object না থাকলে Infinitive না বসে verb-এর সাথে ing যুক্ত হয়।
•  কিন্তু object থাকলে infinitive ব্যবহৃত হয়।
• এ নিয়মানুযায়ী যেহেতু- advise-এর পর me আছে,।